Disability glare: effects of temporal characteristics of the glare source and of the visual-field location of the test stimulus

Abstract

One of the main early complaints of cataract patients, even when these patients exhibit only mild glare problems as measured by standard tests, is that glare impairs their night driving. To provide a better measure of the patients' impairment, glare tests should include measurements of the glare effect in conditions more similar to those found in night driving. During night driving the ambient light is very low, and oncoming headlights present a transient temporal pattern. Furthermore, the objects of interest often appear initially in the peripheral visual field. Thus three important characteristics of glare in night driving are that the ambient illuminance is in the scotopic-mesopic range, the detection stimulus is in the periphery, and the glare source is transient. Most of the current glare testers measure glare only at photopic levels, and all the glare tests that we know of use only steady sources of glare with foveal discriminations. All these conditions are dealt with. The transient glare source raised thresholds by 0.5-0.75 log unit more than the steady glare source, and the transient glare effect was more pronounced and more long lasting in the periphery. Standard glare testers seriously underestimate disability glare effects in everyday life.

Glare Disability and Driving Safety

“…The studies of driving crashes indicate that alcohol interacts with stroboscopic glare to create particularly high risks of crash. The published studies propose that stroboscopic glare effects of lights in tunnels and headlights at night are related to drunken driver accidents [12]. Our studies have shown that a subject's ability to recover after exposure to glare is diminished progressively by consumption of alcohol.…”

“…By assessing the visual functions of a driver during driving in a real traffic situation under various circumstances of weather and illumination (daytime, dusk, nighttime, city traffic, country road), the limits of adaptation to luminance, object size, object contrast and color can be quantitatively determined. For the glare situation, typical values of glare angle and corneal illuminance of the glare light and the induced reduction of contrast can be determined with a potent glare disability test [12,13].…”

Vision and Night Driving Abilities of Elderly Drivers

“…Discomfort glare can be distracting but does not necessarily impair vision, whereas disability glare causes impaired vision (Abrahamsson and Sjostrand 1986;Bullough et al 2002;Mainster and Timberlake 2003). Disability glare is the result of forward intraocular light scattering due to a nearby glare source and leads to a decreased VA and contrast sensitivity (Bichao et al 1995;Bullough et al 2002;Puell et al 2004;Rubin et al 2001).…”

“…In general, the effect of glare will increase with an increasing glare source, decreasing background luminance, and decreasing angle between the line of sight and the direction of the light source (Bichao et al 1995;Bullough et al 2002). Sivak and Olson (1982) showed a significant disability glare effect if the angle of the glare source is very small (0.2…”

“…Disability glare increases further if the glare source appears suddenly and is transient (Bichao et al 1995;Mainster and Timberlake 2003;Werber 2003) because the glare encounters a dilated pupil (Werber 2003). This enhancement during transient glare compared to stable glare increases with increased intraocular scattering (Bichao et al 1995).…”